Apparatus, system and method capable of pre-allocating and communicating IP address information during wireless communication

ABSTRACT

An embodiment of the present invention provides an apparatus, comprising a wireless station (STA) operable to communicate with a first access point (AP) and roam to a next access point (AP), wherein said next AP pre-caches a number of IP addresses from a backend Dynamic Host Configuration Protocol (DHCP) server; and wherein said wireless station (STA) gathers IP layer address and sub-network information from said next Access Point (AP) during roaming.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of Ser. No. 11/107,261filed Apr. 15, 2005, now U.S. Pat. No. 7,463,607 entitled “AN APPARATUS,SYSTEM AND METHOD CAPABLE OF PRE-ALLOCATING AND COMMUNICATING IP ADDRESSINFORMATION DURING WIRELESS COMMUNICATION”.

BACKGROUND

Wireless networks and wireless communication have become prevalentthroughout society creating the need for increased capacity and fasterand more reliable wireless communication techniques. In wirelesscommunication networks, mobile stations (STA) may connect to an AccessPoint (AP) to obtain network service. A STA could be considered“roaming” from one AP to the next AP for a number of reasons. With Voice overInternet Protocol (VoIP) and other real time multimedia applications,the essential roaming requires that a STA be able to quickly establishconnection with the next AP without interrupting the network service.This may also include getting the IP sub-network address informationfrom the next AP as it may be necessary to maintain continuous InternetProtocol (IP) layer connectivity for VoIP and other applications.

Thus, a strong need exists for an apparatus, system and method capableof pre-allocating and communicating IP address information duringwireless communication.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed outand distinctly claimed in the concluding portion of the specification.The invention, however, both as to organization and method of operation,together with objects, features, and advantages thereof, may best beunderstood by reference to the following detailed description when readwith the accompanying drawings in which:

FIG. 1 illustrates an IP Subnet Roaming Information Element of oneembodiment of the present invention; and

FIG. 2 illustrates an IP Subnet Roaming Information Message Exchange ofone embodiment of the present invention.

It will be appreciated that for simplicity and clarity of illustration,elements illustrated in the figures have not necessarily been drawn toscale. For example, the dimensions of some of the elements areexaggerated relative to other elements for clarity. Further, whereconsidered appropriate, reference numerals have been repeated among thefigures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, components and circuitshave not been described in detail so as not to obscure the presentinvention.

Some portions of the detailed description that follows are presented interms of algorithms and symbolic representations of operations on databits or binary digital signals within a computer memory. Thesealgorithmic descriptions and representations may be the techniques usedby those skilled in the data processing arts to convey the substance oftheir work to others skilled in the art.

An algorithm is here, and generally, considered to be a self-consistentsequence of acts or operations leading to a desired result. Theseinclude physical manipulations of physical quantities. Usually, thoughnot necessarily, these quantities take the form of electrical ormagnetic signals capable of being stored, transferred, combined,compared, and otherwise manipulated. It has proven convenient at times,principally for reasons of common usage, to refer to these signals asbits, values, elements, symbols, characters, terms, numbers or the like.It should be understood, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities.

Embodiments of the present invention may include apparatuses forperforming the operations herein. An apparatus may be speciallyconstructed for the desired purposes, or it may comprise a generalpurpose computing device selectively activated or reconfigured by aprogram stored in the device. Such a program may be stored on a storagemedium, such as, but not limited to, any type of disk including floppydisks, optical disks, compact disc read only memories (CD-ROMs),magnetic-optical disks, read-only memories (ROMs), random accessmemories (RAMs), electrically programmable read-only memories (EPROMs),electrically erasable and programmable read only memories (EEPROMs),magnetic or optical cards, or any other type of media suitable forstoring electronic instructions, and capable of being coupled to asystem bus for a computing device.

The processes and displays presented herein are not inherently relatedto any particular computing device or other apparatus. Various generalpurpose systems may be used with programs in accordance with theteachings herein, or it may prove convenient to construct a morespecialized apparatus to perform the desired method. The desiredstructure for a variety of these systems will appear from thedescription below. In addition, embodiments of the present invention arenot described with reference to any particular programming language. Itwill be appreciated that a variety of programming languages may be usedto implement the teachings of the invention as described herein. Inaddition, it should be understood that operations, capabilities, andfeatures described herein may be implemented with any combination ofhardware (discrete or integrated circuits) and software.

Use of the terms “coupled” and “connected”, along with theirderivatives, may be used. It should be understood that these terms arenot intended as synonyms for each other. Rather, in particularembodiments, “connected” may be used to indicate that two or moreelements are in direct physical or electrical contact with each other.“Coupled” my be used to indicated that two or more elements are ineither direct or indirect (with other intervening elements between them)physical or electrical contact with each other, and/or that the two ormore elements co-operate or interact with each other (e.g. as in a causean effect relationship).

It should be understood that embodiments of the present invention may beused in a variety of applications. Although the present invention is notlimited in this respect, the devices disclosed herein may be used inmany apparatuses such as in the transmitters and receivers of a radiosystem. Radio systems intended to be included within the scope of thepresent invention include, by way of example only, cellularradiotelephone communication systems, satellite communication systems,two-way radio communication systems, one-way pagers, two-way pagers,personal communication systems (PCS), personal digital assistants(PDA's), wireless local area networks (WLAN), personal area networks(PAN, and the like).

Types of cellular radiotelephone communication systems intended to bewithin the scope of the present invention include, although not limitedto, Code Division Multiple Access (CDMA) cellular radiotelephonecommunication systems, Global System for Mobile Communications (GSM)cellular radiotelephone systems, North American Digital Cellular (NADC)cellular radiotelephone systems, Time Division Multiple Access (TDMA)systems, Extended-TDMA (E-TDMA) cellular radiotelephone systems, thirdgeneration (3G) systems like Wide-band CDMA (WCDMA), CDMA-2000, and thelike.

An embodiment of the present invention provides a solution for interIP-address roaming for wireless communication devices, such as but notlimited to, the Institute for Electronics and Electrical Engineers(IEEE) 802.11 wireless stations, using for example, but not limited to,MAC layer messaging. The present invention may provide mechanisms forinter IP domain roaming. In addition, an embodiment of the presentinvention may provide an IP address caching scheme at Access Points, sothat roaming stations can preview their new IP layer characteristics atroaming time. Also, the binding of DHCP lease with PMKID lifetime isprovided in an embodiment of the present invention.

An embodiment of the present invention provides a mechanism for awireless station (STA) to gather IP layer address and sub-networkinformation from the next potential Access Point (AP) during roaming.This information includes a STA's new IP address, new subnet mask,default gateway router address, and lease time of the new IP address. Anembodiment of the present invention prescribes that the next APpre-cache a number of IP addresses from the backend Dynamic HostConfiguration Protocol (DHCP) server. Pre-caching IP addresses from thebackend DHCP server at the next AP may prevent the STA from performingexpensive DHCP messaging to the backend DHCP server at roaming time.

Thus, an embodiment of the present invention enables wireless clients toselect the next Access Point in the multi-cell overlapped environmentand improve roaming performance for time bounded traffic. Determiningwhether the wireless client decides to roam to a new IP subnet and IPaddress, associated with the next AP, may impact overall applicationperformance. The present invention may minimize roaming impact, improveoverall roaming efficiency and application performance. Further, anembodiment of the present invention may be used in handheld wirelessdevices and mobile platforms to enhance Voice of Internet Protocol(VoIP) performance and enable a richer wireless local area network (LAN)experience for real time multimedia mobile users; although it isunderstood that the present invention is not limited to these uses andare merely illustrative the possibilities.

In an embodiment of the present invention, the information that the IPsubnet roaming information element for the Access Point should providemay include the following:

-   a. IP Address: This is the new IP address that the STA will be    obtaining if the STA roams to a particular AP.-   b. IP subnet mask: The IP subnet mask determines the network address    and host address portion of the IP addresses. This will indicate the    number of bits in the subnet mask.-   c. Default gateway router address: This is the next hop router    address on the new subnet.-   d. Lease time: The next AP will allocate an IP address lease time    which will be the shorter of that allocated by the DHCP    administrator and the Pairwise Master Key Identifier (PMKID)    validity time.

The flow for pre-caching of IP address information at the next APs mayinclude the following in one embodiment of the present invention:

-   a. The next AP may pre-cache a limited number of IP address from the    network DHCP server. Thus, the next AP would perform DHCP messaging    with the DHCP server to procure IP addresses before potential    wireless devices roam to this AP.-   b. When a mobile wireless device performs Re-Association Request,    Resource Query, or Resource Reservation, as defined in proposal for    802.11r (it is understood that the preset invention is not limited    to 802.11r nor any particular requests, queries or reservations),    with the next AP, then the next AP will indicate new IP address    parameters to the mobile wireless device.-   c. Once the wireless device decides to roam to this AP, it already    has the new IP address, and can perform additional higher layer    functionality necessary for roaming.-   d. The next AP may remove this IP address from its list of    pre-cached IP addresses, and may query the DHCP server to get some    more IP addresses. Likewise, the AP may also release IP addresses    that it pre-cached back to the DHCP server.

Turning now to FIG. 1, shown generally as 100, is an illustration of anIP Subnet Roaming Information Element of one embodiment of the presentinvention. The IP Subnet Roaming Information Element (IE) may be definedas shown in FIG. 1 for IPv4 and IPv6 networks (although it is understoodthat the present invention is not limited in this respect or to aparticular IP version). “XX” refers to the variable length field, whoselength is determined by the length field preceding that field. TheAccess Point may include a IP Subnet Roaming IE in the Beacons, and/orProbe request/responses to advertise its roaming capability. The AccessPoint may also include an IP Subnet Roaming IE in the Action,Re-Association, Query messages, or Reservation messages as STA requests.

Referring now to FIG. 2, shown generally as 200 is an illustration of anIP Subnet Roaming Information Message Exchange of one embodiment of thepresent invention which depicts the message flow path. Access Point 210uses DHCP messaging to communicate with Network DHCP server 215 in orderfor Access Point 210 to cache IP addresses. A probe response (IP subnetRoaming IE) 225 is sent from Access Point 210 to Wi-Fi Mobile Station205. It is appreciated that the present invention is not limited to anyparticular wireless devices and a Wi-Fi wireless device is used hereinfor illustrative purposes only. Or a just-in-time 802.11r ProposalRe-Association Request may be sent from mobile station 205 to AP 210.Again, it is understood that the present invention is not limited to802.11 r or any particular wireless standard.

A Just-In-Time Proposal Re-Association Response (IP Subnet Roaming IE)may then be sent from AP 210 to STA 205 or a Just-In-Time Proposal QueryResource Response (IP subnet roaming IE) may be sent from the STA 205 toAP 210. Subsequently, a Just-In-Time Proposal Query Resource Response(IP Submet Roaming IE) may be sent from AP 210 to STA 205. Again, it isunderstood that the present invention is not limited to 802.11rJust-In-Time proposal or any particular wireless standard.

An embodiment of the present invention enables a wireless device (suchas, but not limited to Wi-Fi 802.11 wireless mobile devices) to roam toa next AP which may be part of a new IP subnet. In this case, the mobiledevice will need to know if it has crossed the IP address subnetboundary, and if so, get a new IP address. This problem is not beingaddressed currently in existing wireless communications. An embodimentof the present invention may inform the wireless device a priori that itmay be crossing into a new IP address subnet.

Existing art has not provided a mechanism with which to indicate thepotential new IP address to the roaming wireless client devices. Anembodiment of the present invention provides a solution for wirelessclients to get a new IP address within a wireless framework (such as,but not limited to the 802.11 framework). By providing that the next APpre-cache a limited number of IP addresses from the backend network DHCPserver, this will prevent a mobile wireless device from performing timeconsuming and complete DHCP messaging at the time it is roaming. Thenext AP will be able to allocate one of the cached IP addresses to themobile station.

An embodiment of the present invention may tie the DHCP lease time withthe lifetime of the PMKID at the AP and STA and may limit the livenessof the IP address to be bound by the lifetime prescribed by the DHCPadministrator, or by the lifetime of the PMKID, whichever is shorter.This is then, communicated to the station in the prescribed messages.Thereby, a mechanism for a STA to gather IP subnet roaming informationfrom next potential Access Point, such as, next potential Access Point'sIP subnet information, default router, and potential Wi-Fi station's newIP address information is enabled. A wireless station, such as a Wi-Fistation, may use this information to decide if it would like to roam toa new IP subnet and may prepare the upper layer network stack andapplications for IP mobility.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those skilled in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

1. An apparatus, comprising: a wireless station (STA) operable tocommunicate with a first access point (AP) and roam to a next accesspoint (AP); wherein said next AP is configured to pre-cache a pluralityof IP addresses from a backend Dynamic Host Configuration Protocol(DHCP) server; wherein said wireless station (STA) is configured togather IP layer address and sub-network information from said next APduring roaming; and wherein said next AP is configured to limit a leasetime of at least one of the plurality of pre-cached IP addresses to theshorter of a DHCP lease time allocated to the at least one pre-cached IPaddress by a DHCP administrator or a Pairwise Master Key Identifier(PMKID) validity time associated with the next AP and the wirelessstation (STA).
 2. The apparatus of claim 1, wherein said IP layeraddress and sub-network information includes said STA' s new IP address,new subnet mask, default gateway router address, and lease time of saidnew IP layer address.
 3. The apparatus of claim 2, wherein said STA isoperable in multi-cell overlapped environment and adapted to select saidnext Access Point to improve roaming performance for time boundedtraffic.
 4. The apparatus of claim 1, wherein said first AP provides anIP subnet roaming information element that provides an IP Address thatsaid STA will be obtaining when roaming to said next AP.
 5. Theapparatus of claim 1, wherein said next AP provides an IP subnet roaminginformation element that provides an IP subnet mask that determines thenetwork address and host address portion of the IP addresses.
 6. Theapparatus of claim 1, wherein said next AP provides an IP subnet roaminginformation element that provides a Default gateway router address. 7.The apparatus of claim 1, wherein said next AP is capable of includingan IP Subnet Roaming information element in a Beacon, and/or Proberequest/response to advertise its roaming capability.
 8. The apparatusof claim 1, wherein said next AP is adapted to include an IP SubnetRoaming IE in the Action, Re-Association, Query messages, or Reservationmessages as an STA request.
 9. The apparatus of claim 1, wherein saidnext AP uses the following flow for pre-caching IP address informationat at least one additional AP: said next AP pre-caches a limited numberof IP address from a network DHCP server with said next AP therebyperforming DHCP messaging with DHCP server to procure IP addressesbefore said STA roams to said at least one additional AP; when said STAperforms Re-Association Request, Resource Query, or Resource Reservationwith said next AP, then said next AP will indicate new IP addressparameters to said STA; once said STA decides to roam to said next AP,it already has a new IP address, and can perform additional higher layerfunctionality necessary for roaming; and said next AP removes said newIP address from its list of pre-cached IP addresses, and can query saidDHCP server to get additional IP addresses.
 10. The apparatus of claim1, wherein said STA is a Wi-Fi Mobile Station.
 11. A method, comprising:communicating by a wireless station (STA) with a first access point (AP)and preparing to roam to a next access point (AP) that has pre-cached aplurality of IP addresses from a backend Dynamic Host ConfigurationProtocol (DHCP) server; gathering by said wireless station (STA) IPlayer address and sub-network information from said next AP; and whereinsaid next AP is configured to limit a lease time of at least one of theplurality of pre-cached IP addresses to the shorter of a DHCP leaseallocated to the at least one pre-cached IP address by a DHCPadministrator or a Pairwise Master Key Identifier (PMKID) validity timeassociated with the next AP and the wireless station (STA).
 12. Themethod of claim 11, wherein said IP layer address and sub-networkinformation includes said STA' s new IP address, new subnet mask,default gateway router address, and lease time of said new IP layeraddress.
 13. The apparatus of claim 12, further comprising operatingsaid STA in a multi-cell overlapped environment and adapting said STA toselect said next Access Point to improve roaming performance for timebounded traffic.
 14. The method of claim 11, further comprisingproviding by said first AP an IP subnet roaming information element thatprovides an IP Address that said STA will be obtaining when roaming tosaid next AP.
 15. The method of claim 11, further comprising providingby said next AP an IP subnet roaming information element that providesan IP subnet mask that determines the network address and host addressportion of the IP addresses.
 16. The method of claim 11, furthercomprising providing by said next AP an IP subnet roaming informationelement that provides a Default gateway router address.
 17. The methodof claim 11, further comprising including by said next AP an IP SubnetRoaming information element in a Beacon, and/or Probe request/responseto advertise its roaming capability.
 18. The method of claim 11, furthercomprising including by said next Access Point an IP Subnet Roaming IEin the Action, Re-Association, Query messages, or Reservation messagesas an STA request.
 19. The method of claim 11, wherein said next AP usesthe following flow for pre-caching IP address information at at leastone additional AP: said next AP pre-caches a limited number of IPaddress from a network DHCP server with said next AP thereby performingDHCP messaging with DHCP server to procure IP addresses before said STAroams to said at least one additional AP; when said STA performsRe-Association Request, Resource Query, or Resource Reservation withsaid next AP, then said next AP will indicate new IP address parametersto said STA; once said STA decides to roam to said next AP, it alreadyhas a new IP address, and can perform additional higher layerfunctionality necessary for roaming; and said next AP removes said newIP address from its list of pre-cached IP addresses, and can query saidDHCP server to get additional IP addresses.
 20. An article, comprising:a non-transitory storage medium having stored thereon instructions,that, when executed by a computing platform results in: communicating bya wireless station (STA) with a first access point (AP) and preparing toroam to a next access point (AP) that has pre-cached a plurality of IPaddresses from a backend Dynamic Host Configuration Protocol (DHCP)server; gathering by said wireless station (STA) IP layer address andsub-network information from said next AP; and wherein said next AP isconfigured to limit a lease time of at least one of the plurality ofpre-cached IP addresses to the shorter of a DHCP lease time allocated tothe at least one pre-cached IP address by a DHCP administrator or aPairwise Master Key Identifier (PMKID) validity time associated with thenext AP and the wireless station (STA).
 21. The article of claim 20,wherein said IP layer address and sub-network information includes saidSTA' s new IP address, new subnet mask, default gateway router address,and lease time of said new IP layer address.
 22. The article of claim20, further comprising further instructions that, when executed by acomputing platform results in operating said STA in multi-celloverlapped environment and adapting said STA to select said next AccessPoint to improve roaming performance for time bounded traffic.
 23. Thearticle of claim 20, further comprising further instructions that, whenexecuted by a computing platform, results in providing by said first APan IP subnet roaming information element that provides an IP Addressthat said STA will be obtaining when roaming to said next AP.
 24. Thearticle of claim 20, further comprising further instructions that, whenexecuted by a computing platform results in providing by said next AP anIP subnet roaming information element that provides an IP subnet maskthat determines the network address and host address portion of the IPaddresses.
 25. The article of claim 20, further comprising furtherinstructions that, when executed by a computing platform results inproviding by said next AP an IP subnet roaming information element thatprovides a Default gateway router address.
 26. The article of claim 20,wherein said next AP uses the following flow for pre-caching IP addressinformation at at least one additional AP: said next AP pre-caches alimited number of IP address from a network DHCP server with said nextAP thereby performing DHCP messaging with DHCP server to procure IPaddresses before said STA roams to said at least one additional AP; whensaid STA performs Re-Association Request, Resource Query, or ResourceReservation with said next AP, then said next AP will indicate new IPaddress parameters to said STA; once said STA decides to roam to saidnext AP, it already has a new IP address, and can perform additionalhigher layer functionality necessary for roaming; and said next APremoves said new IP address from its list of pre-cached IP addresses,and can query said DHCP server to get additional IP addresses.
 27. Anapparatus, comprising: an access point (AP) operable to communicate witha wireless station (STA) and facilitate roaming by said STA to a nextaccess point (AP); wherein said next AP pre-caches a plurality of IPaddresses from a backend Dynamic Host Configuration Protocol (DHCP)server; wherein said wireless station (STA) gathers IP layer address andsub-network information from said next AP during roaming; and whereinsaid next AP is configured to limit a lease time of at least one of theplurality of pre-cached IP addresses to the shorter of a DHCP lease timeallocated to the at least one pre-cached IP address by a DHCPadministrator or a Pairwise Master Key Identifier (PMKID) validity timeassociated with the next AP and the wireless station (STA).
 28. Theapparatus of claim 27, wherein said IP layer address and sub-networkinformation includes said STA's new IP address, new subnet mask, defaultgateway router address, and lease time of said new IP layer address. 29.The apparatus of claim 27, wherein said next AP uses the following flowfor pre-caching IP address information at at least one additional AP:said next AP pre-caches a limited number of IP address from a networkDHCP server with said next AP thereby performing DHCP messaging withDHCP server to procure IP addresses before said STA roams to said atleast one additional AP; when said STA performs Re-Association Request,Resource Query, or Resource Reservation with said next AP, then saidnext AP will indicate new IP address parameters to said STA; once saidSTA decides to roam to said next AP, it already has a new IP address,and can perform additional higher layer functionality necessary forroaming; and said next AP removes said new IP address from its list ofpre-cached IP addresses, and can query said DHCP server to getadditional IP addresses.